SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37ce455ee162d02f46747385a8f8bcf7af926d03a26f8f5e050540acce2e8b3f' 
  AND token = 'vxG5y9Lqn+jYWa/AVOln57kHje9KxLu7B1LBvo+XvBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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