SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f7ff6d01f8700db99d2eaba3426cce43dd11214dac1905d62c76c8fa7548371' 
  AND token = 'JpXBq977AhKMJtsYmuaPdsCWBvO2qLQxFjNMm+TpCmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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