SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad321897c2feb8874478781f779f47cf7f53d82eb10b1a4d1996538da0c35472' 
  AND token = 'RCv8Iv7bF0VY+fvKC3BESzaKMZVswl2Xg1fP3g5YSLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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