SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc9460035830bc32aca393da689e3bae03b4271d56d962d6171983ffde6301f3' 
  AND token = 'n8sCMSPxp0m1lSVyW8pb4DbLfiugexratQbXySZfQTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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