SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85a21ca6b756110efbd62e572501e5549fd1dd59b72d6813b5f1b263c23b6292' 
  AND token = '3OTBJE4yk7MHTvrkcCCpotJhLXsqehR/FpQ3phOc4Zc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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