SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '833d39bc305b118f850141f49d8c63dc560271f67c604ae194494436510e9bac' 
  AND token = 'B3IP5pm15IoOlvKaKHN5afxWijR08Dnq31O7GBpz4Nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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