SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c55a1efdaf2ba106b0adfeb2edddac739f576dd0ef9a3c59cdfefd515d39f48' 
  AND token = 'y/QhTxuSpi94C6PdAHnHXXsfBVrCp1g7rX314lKEVkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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