SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b859fb6dc0d1e236cdb4829f8b3e7f829cd9f5a234107506b935c657932ee91b' 
  AND token = 'LAvQhvAXLk5fpYb5BTSjNqUoB8YkB3k4vxOAoYQzuAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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