SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a294adb97bb0e74e03ca81b489799bb28af7176b32635624f63517087a77324' 
  AND token = 'FWJmGQbtqkXR0g/cR+xHNib3KyFNgbCVWSG0uC3RYjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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