SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '190f8be4631844235f60719e36a0b668dc9f7e77854c24234c743798c9bc5226' 
  AND token = 'n+BFVdsEttz2Rg37mow1hVXNeGGsXAsvR0Q58Yp1x8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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