SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38203673edcd97a798521f879f2638686f064491e506ddb2adce6b5c7fe015b0' 
  AND token = 'pCwXVrTTi8ifSsm8jCdfa++4ka0lotXJEIQ7hff+SCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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