SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f432e914480aad8524aebe5a3d46edaf1cf256037a822bcc1267efd61a047802' 
  AND token = 'A3CULrvGK+bgMslth5DY7djLJjw0tR7wuFDtru6Jpig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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