SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8090bbc0e9d803ca5265db402c489bfa1da7de1a0ceeb602224f584154e815a5' 
  AND token = '3jr9lBicakFXSsQdaCOo+Liw7WPJP19BbcKE9rzfXYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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