SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a3d792e88258dea4e8d7ac1c46bed6bc33df96fd2e8281712ded1b17506e105' 
  AND token = 'x7L2erk3zLa3BL0VIMV9vznTN+PuKdp/giV7u56yEAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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