SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c56a246f61ddeba51d87f99f8fe15a8ccf2c1a02239a3b95cc26038a334d73b' 
  AND token = 'TlMpr8UuoICcZSvqothS06zuHHZDerWpMASZR2Sf33g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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