SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408466e9f47e8ca4bcceadb11993bf625f9626d2b5a8080dcedca50f097a99a6' 
  AND token = 'vziNGUYfU+V7lXo4wci3fM2q8SPv4HT25o5Zc3LyDEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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