SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '646db9f99b1a7a31f39bb95f3f6e5500e7514130137383a3af8479a50bce8ec1' 
  AND token = 'zvPNx4cyuO9NCZVvedCRJv5ttHPk6AZ6fwwFTHI4Iws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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