SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02a6b21f6300a932cefd7914d40d771de5d08a2634b0f2c6f6255aa37237f6c3' 
  AND token = 'EKVjqc2IaClL4U04goIKOE3dyMrLo67Tfuhr4zh9Z54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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