SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55bc6b1f2e8781d0e49e5a76613cf8ec5f2eef641ad1d2e546e41d97789bd69c' 
  AND token = 'u1ZO/jqbYdEbv6VD9G31VP3TmK5tLFwX+vNab2PQLnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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