SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9dcccaa84223476aff2316b7bbb4be23c8389cdb494c3537579cb3504284541' 
  AND token = 'WqOVVk+umO71twzlYY9OqEzMdYPsOX4/aSt7uU7OAXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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