SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e8e1f55010559d4d6f32a6f80f06603c4e5d26e0bc4d078bdd66a8f7e463c51' 
  AND token = '4BOs8KUx6qpcmXZLz/lZqsCFUei3gFmv+NnfBgJrQiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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