SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd862bb251e8c02fe4ea588098951d132f98ee94973aeb4faef8294bd8bbb74a6' 
  AND token = 'nKbVdzNxp7Tsr6tyGUaPGhe3pvKbF4Hgn68D4vH8oCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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