SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e3b4dae0864af631f10d4b2411ff5e72f224b7fb4eb58d0f2c037a2043b01c3' 
  AND token = 'kHYCMZAjXmpyPSrp07lpmHDcnKtSOcGlsjHvgGXqvfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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