SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77212d81f7b195e72931168ad314d1da84299383bedf59f3308f488a06c5b48d' 
  AND token = '2IGicvqj/nkgPhmCdlBvoBG9x2Lyn8nFU7hBfvLE+G8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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