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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '918b161781afaeb26b40528f7809a9dfc082e06da923cfed8017c0fbbf5efd61' 
  AND token = 'guy0vrZ4Hk8FRH3P7cQ8EoIx+0RrezYvETYqCPpGQUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}