SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bfa5d885165381adde5b23f5f6bcbed9568fc1ac815afd1fc4e07efdc38c146' 
  AND token = '6tmyLEbmnOeeWxSKjjOmBNFd6rEn/johnBPpn2ryA2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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