SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f09cb1c12102326ca1a8c174d6448fc69b4e3c16cd2461a6a41dd52976e3ca41' 
  AND token = 'NM7DwwYIcOoM3i5ojyVSPE2XU3csMhUyhyARbCHXmfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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