SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99782c7fa1534274b1fbf784bb89aa0d92538936b8beceea11eb530742dc81c5' 
  AND token = 'vslSTHvZYCsi4IMyQPXFDr2IAGhJ46JhdKLhtPa+oM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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