SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57d5cde883dfccc355e101adedba745855234e7ec6dac70169f802d16aaecfb' 
  AND token = 'w6fo2IX9kVK1yaCp5t3PP/IfF28JehQuXjw5pxy1CEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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