SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58c1597fe1a4b5d1f7bdfd2fc6251d91fe149c63312e3cb06906cc663f929477' 
  AND token = 'cWCy4BLDHeSzjDv7+QIu0aHUgd0kgHsetfvByIaNgL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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