SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9843878cd0d59b422b2bfd99fd40b57c5d43c038e34798060780661b2c51fe89' 
  AND token = 'Z5tZ9ksk/DPKoH1K9OPHmxL1GUeOUAi1wV6uFTNjZ7M=' 
  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"
    }
  }
}