SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e8673d4cf101a496de0264db10fc3b91254c27ea54d5a865b570d442eddc785' 
  AND token = 'q4PyNSPYNo72VAVnnklgMGGWWqNTIMpQGyuxeTn0XpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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