SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e88b0537efa6ab0a33ae869936d48fcd3bcd6e4c69ae378b17289f0658ddb9cf' 
  AND token = 'FmGLbd0HviCX/j61eVtaNgfiKBlSRGSiUCdLv3iFaOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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