SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb7e15932ee08843b37a409ed115a46cf7f38b7a2c701472aefb8c7f81bad949' 
  AND token = 'FHrOLz8zxZMu3vzKlej5M9DYbLmwl3dEmyu3hJJurGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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