SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8a89d82b0e1e2c58a5da166e9c108a89b48b7209b472c7116ddc1db0334bb0c' 
  AND token = 'yGfddcz+kT991UAzyxSCqacu8zgwSjy3zFfSk5xyVl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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