SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d18155ce58809dc7bb9ccffe9955b1650f692ca1b586710b53cdeae7120d30e' 
  AND token = 'vEtMzcyd91NO5/mAgrvXOzGwhaayMjenSDDsd1KMRT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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