SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5994611314e55d06e66b9ceff1926da5d269751c1db2e3d75d1c292047bb428' 
  AND token = 'YE6ehNNbcJEO+a+imGeR1LWs3DnNyAFleyu4YVNyqkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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