SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ce079454edb1840766c6f628c2122b2dd787b7e7928e812639cf364afa5dcfb' 
  AND token = 'LVT3kwRiXKeUQCifEHf+lqTHICA51MVCGZXAFdqJ8iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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