SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '451f36ccf3f3dae083cc05835696addd8192b3376fb6f7ccfba97ad3bda8e102' 
  AND token = 'yTFfTlCsBA09TlU3Zcu2HazFxbHpaOFHiEBbceFm2BY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}