SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f20a8df8c96832ad4f2f430ace4172541eaf2a2907d098527bef00317d43ff' 
  AND token = '0j6AhQJhXJn6ixaNWf11jMwYxHutWYtct9gDhcDlUdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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