SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9305898bbea2f76f705ff38d6397b2c9a940ed1758cef7e76801b28ba0298ac' 
  AND token = 'zFHH4GmGstXjiaw0xxJPDbiLnsvLxsDS1e0eK0Tf2xA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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