SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e15ab54cee44172f0af8f6a799b6b89f56a14d716df3add4ee814dfd36c8d19' 
  AND token = 'G6PlexhKv23Rdz1rMffRZ7DRbiJHqEqJ+vxjz1BnYcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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