SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d08edbac789c25b02edf7e80c4e79f62ae36b9448eb4f33cd81fd2bc60b879' 
  AND token = 'FCHcjEA5r43/nkZqBUspmF3LQTgA2x8njdH5Rjud+N4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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