SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c527118f78e0a0bbf6824cf8825a1895b591964beff8f13f1970a3d084e8c037' 
  AND token = 'Yri2wNP0GSsaMrqgaVJIpKEvb/UPupiuhMLelzBU/D8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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