SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd92df37d51f9f0fb2bd301210852ac4b3f8999f5a679d4f6557ad4773005eacd' 
  AND token = 'rs1ZLwsP5WgCm/Grr5PWXs5AIah+CKRq6GWWTHLChwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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