SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0a00c2cd60ca1d32005804cd806f5889fea09a932574b661a78ec211f892b9' 
  AND token = 'Eih+djbSdko2a50eqsfdXjS54zi6VCdgq+96gKz331Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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