SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10b0b4e99b9b6a4964d3352c61304047b1f18c054eae87aaab58653ba9a1d0bc' 
  AND token = 'fSthmgLfrYOZ0vzAxYdUuwwdWLFZrBxe+PkJ+ZyMHi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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