SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adb0a0575b384dffb29ae682bb903327bbfba6afc8648d093aa81f8e821d6547' 
  AND token = 'i20K2acEV48DM72Nx+TR2Oy31kGlJjdq/2uGwcfIbDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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