SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8a7cf66349142869609eea48df744eaa769b6866bb14d09b3eefd32adf3aaf2' 
  AND token = 'oh3SOpfvcMob/4UFiBSDX+rLLvSd5jdtKXfGkgMg3nA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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