SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a595378db8516e27ffc646bd74efad01380f886c7b384532ec5d0d0c978c1f' 
  AND token = 'eTJQyMW0CTK1uEASpkgGkFJt/OXsnjBLecpcpVWVe7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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