SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5658f0be0bba051bcdb0914221594d4da171ab8710a7235b3c063d2918d5e28' 
  AND token = 'REOR3tbpsx+wDgb2HRPc+VeOzyji4GVLJ3qSMYz19Tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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