SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acffbf5ec6f2ddb879661aa9dfb1a02fe9aa56b021f4ae337889f6ff3acbddc5' 
  AND token = 'MwXPSGC8frdKjdwDNhi1o4+29pXnpAHzWXku7e+CcR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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