SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12b3e67928037be72e13426041ae89d26ecec1cf55dd4427b9fcd6dbf08ac0b4' 
  AND token = '0WqgQyXZC4oL8tPCtJjbdYlApbQR9hBoxNjKZSzckdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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