SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f47334f04df159c0a89b8bcfc4c213af0d097a24eb9912f921569c08c288630' 
  AND token = 'VhkmWLZff8g1UYm5Xlj2RHJVsbIxkqCTfgJZ/rhPPgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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