SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75e6705a61f022b5454f7d4134242f01b51b68e714c096412386945e1ad42a1b' 
  AND token = 'HhfGA3AHYJsNryra9EQwmk1bEw6GgPzu6MNoFgMmrkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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