SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab21c3b4a3de9411cbe1e72f509ed919e7d510c942fa772065b02b9f882179c9' 
  AND token = '0NBH3pk3bXHlroUNqkayTBLo6um5bbtnPXIzuat+sK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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