SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596959c961dd88d0ff4f36852d4c453893c3614df88e5392755f586963900c23' 
  AND token = 'juPJOep2VHsZ7C53PqMKHlzNAjunq66/KCTfuD8JMz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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