SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e81d245dac535adb402dee9d968d577ca2aff5cdaebc1cf07c6d4cfe06a86719' 
  AND token = 'PAtfsCZVv/ghgKGzujVZd7/xbmQEQaVKmkYyJh0hOok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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