SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7d8960ca7fc39b16472a3d81b9e9165294994348c3df6e3cc67d5d857926116' 
  AND token = 'GNWZBmQEyXgJYGrgQK2Xc+k/4nlWxJ/KM7izg2xEMGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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