SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a475cd177f48671af18fd4d449d90db636429980525bd736509cdd02018a99c' 
  AND token = 'NskdHFbk4F7nDvZ0MffGUjwtOi7+idcilsBNpczI5Z0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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