SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1fac4003adb604dd8d2044cc76d549ade374171cc1f205bc11e40866eb25456' 
  AND token = 'eGlPwSdyEXPtK6mtPDHoFQN++PVtYngjlEGZg+8Wkvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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