SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e8b18f5f20f8498a494d12bca2400ada8e8bab0ae5c390931205587794fb559' 
  AND token = 'UAzXFGYBM4WllvZ/50qNQ4hYeYamm0ufoPISNHKJTjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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