SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51debd1b44e04a1e2d9c467c3eb843006bfa561fc09316d50ddbbd45bbbf1f73' 
  AND token = 'YGfx7sHwhLArIyJ0FmpMsglStzXv2lVWFHUoo+To+Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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