SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31396d82aa9bf1e389312d7429b1f7e7823b39cfd3393be962670fbf0ac0fb9c' 
  AND token = 'z3PtEVQijVsV/yubAMEKSAxAlIdPg9iPZr6Zx9fiISA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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