SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '308404a81555346b313d006f426ba09d5de0190cb50f83e051f39ea3480981d4' 
  AND token = 'gKGv+TeY+5K3Aotk/H2bnx2pA4BLdnFGUjpxOKMpmuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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