SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '434d14c7debe3a6d1ea608a53f536a031932dab83740bcc65d86f2378843826e' 
  AND token = 'oLAMk5S+0VkOdd3AnRowmGUeXhZmhxAMvEK0pVMcjzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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