SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a3b6cf514cdcd5c17688198f061fb5db89d82e502847f05b61d9ceb5fb0004' 
  AND token = 'txOLqbRMoDzJ5dYtgSrSnwd2pkFWPND/mwg0uZxtKco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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