SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c68f1e8347a40610288ea026ac1b39f43eaefe2c26716886dc456c9eccc0fbea' 
  AND token = '+hzneNuuLQMxBkg7ZxbQi3KjYT5PAW8cEnOvo26zmkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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