SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f4b20b7b4b5148aabf4c7875ae57deb3897a0d52d9394d3dc5722d69ca9be99' 
  AND token = 'GSR1QZFvODofqB/eICbp18CU1uvxxyIIJ+mOkb3g3CY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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