SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a4fe80b315b33818ba19709d08936d331b8f888c9cf32c3cc0a89bb84c64c18' 
  AND token = 'nRqQJkfTecKvVUEFTPvVVccyPKYqYZl+iLJrrO8h0W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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