SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '575b94202260b706722f69994bef9980eed81489239349bc31bcbd775d0ddee7' 
  AND token = 'frTaapaiiqVz253PSNET6jjkSaIvXLre9apmCYQdKhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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