SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b31d6dbbaa58f2fc98b92d908c44f78396f1daa75820e142fd92f39a247c95f5' 
  AND token = 'r6O/6mP7VyECSBW+cAadaHqLLVRjYUVoNqSvTGowtSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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