SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85ae981779629f5057f07cbf59746ae38b0965c6183c2103ffb2bfd3d197e83d' 
  AND token = '8c1k3mKyvBA99mkZwCXw2qZyJgKxw6gdQ/Y8rkQZT5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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